- In the highlighted lines, 2 fits only in the highlighted cells.
- Whichever cells take 2, each crossing line gets one of them.
- So 2 can go nowhere else in the lines that cross them.
Jellyfish in sudoku
A Jellyfish is the next size up from a Swordfish. Take one number and four rows where it can go only in cells of the same four columns. The number can then be removed from the notes of every other cell of those four columns. Rows and columns can swap roles.
Or scan with your phone
How to spot it
Pick a number that is noted in many cells, and look for four rows whose cells for it, put together, fall into four columns. Unless the number is still missing from almost every row, a Jellyfish in the rows comes with a smaller fish in the columns, which is found first. That is why the pattern is rarely needed.
Why it works
Four rows need the number four times and have four columns to do it in. Each of those columns gets the number from one of the four rows, and no other cell of the columns can hold it.
On a real puzzle
This is Jellyfish on its practice puzzle, at the first step that needs it. The game's hint explains the step like this:
Practice it
No level of the game needs Jellyfish, so this practice puzzle is harder than Extreme, its hardest level. Fill in what you can, then look for the pattern, or ask for the hint: each game has one.